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Connection working fine but SMTP port forwarding stops working

eldridgep
Newbie
Posts: 6
Registered: 22-10-2015

Connection working fine but SMTP port forwarding stops working

Not in any way suggesting this is an issue with PlusNet but looking for some feedback, happy PlusNet user myself and I have a client on an ADSL Plusnet service using a Draytek 2860 router and the connection is solid but after a few weeks they stop receiving e-mail messages to their on premise Exchange server (SBS 2011). Now the internet works fine and the server is receiving message from inside the LAN I can telnet on port 25 and fake messages which are delivered however externally all traffic from port 25 to the server is stopped. The solution is very simple reboot the router and mail starts flowing again, either resetting the router or resetting the connection is enough to solve the issue and return mail flow each and every time,
They had an old Draytek 2820 on the same line which showed the same issue so thinking it may be router related we replaced it with the Draytek 2860 but within 3 weeks of it going in they had the same issue, I've put in a work around to schedule a router reboot weekly out of hours but that isn't solving the issue. So we have 2 different routers on two different firmware's seeing the exact same issue.
We have Draytek's rolled out on hundreds of sites and I can honestly say I've only seen this issue once before and it was on a BT Fibre line and it was resolved by replacing the BT OpenReach modem the router was connected to, strange I know but it worked.
Can you see if there is anything  odd on the line if I provide you with the username of the client via PM? Or have you seen this issue before and have any suggestions?
2 REPLIES
Moderator
Moderator
Posts: 18,703
Thanks: 1,956
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Registered: 11-01-2008

Re: Connection working fine but SMTP port forwarding stops working

Does you client have static ip?Huh

Customer / Moderator / If it helped click the thumb / If it fixed it click 'This fixed my problem'

eldridgep
Newbie
Posts: 6
Registered: 22-10-2015

Re: Connection working fine but SMTP port forwarding stops working

Yes they do and there is a CNAME on that which we use for RDP access, HTTPS access and for the MX record that mail is forwarded from.
All other access works fine it is just SMTP traffic that stops forwarding. Power cycle the router and with no other changes made anywhere SMTP jumps back to life and works fine.